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Saint-Martin-de-Londres, France

Hoang T.M.P.,Societe Nationale des Chemins de Fer SNCF | Hoang T.M.P.,CNRS Mechanical and Civil Engineering Laboratory | Saussine G.,Societe Nationale des Chemins de Fer SNCF | Dureisseix D.,CNRS Contacts and Structural Mechanics Laboratory | Alart P.,CNRS Mechanical and Civil Engineering Laboratory
European Journal of Computational Mechanics | Year: 2012

Numerical simulation with discrete elements leads to several issues for large-scale problems and long loading times, as for the granular dynamic simulations of the ballasted railway behaviour. To reduce computational costs, we study the use of two strategies: domain decomposition methods and shared-memory parallelisation with OpenMP. An example of a maintenance process, the tamping, on a portion of railway track with seven sleepers, is simulated. © 2012 Taylor & Francis.

Hoang T.M.P.,Societe Nationale des Chemins de Fer SNCF | Alart P.,Montpellier University | Dureisseix D.,Montpellier University | Saussine G.,Societe Nationale des Chemins de Fer SNCF
Annals of Solid and Structural Mechanics | Year: 2011

The paper is devoted to the development of a non overlapping domain decomposition method suited to granular dynamics. The formulation and the efficiency of such a method are well established for structural mechanics. In order to extend this approach to granular systems a so-called primal splitting of the domain is chosen because it is a less intrusive method for software development. Once the interface problem is defined and the solver is slightly enriched with some extra numerical parameters, the method is tested on railway ballast simulations for improving the maintenance of railway tracks. © 2011 Springer-Verlag.

Cui Y.-J.,ParisTech National School of Bridges and Roads | Lamas-Lopez F.,ParisTech National School of Bridges and Roads | Lamas-Lopez F.,Societe Nationale des Chemins de Fer SNCF | Trinh V.N.,ParisTech National School of Bridges and Roads | And 6 more authors.
Transportation Geotechnics | Year: 2014

As opposed to the new ballasted railway tracks where a sub-ballast layer is often emplaced, the conventional railway tracks were constructed with ballast directly emplaced on the natural sub-soils. Thereby, a layer of mixed materials, namely interlayer, was formed over time mainly by interpenetration between ballast and sub-soils. As this layer plays an important role in transmitting load to the sub-soils, its behaviour under the effects of dynamic loading and climate changes is of primary importance for the stability of tracks. In order to understand the behaviour of the material in such interlayers, field monitoring was performed at a selected site in France, namely Moulin Blanc. Firstly, site investigation was done by borehole, allowing the interlayer location to be identified. Secondly, the interlayer was instrumented with suction probes, temperature sensors and accelerometers at different depths. Two piezometers were also installed for water table monitoring, and a weather station was installed for air data monitoring. The data recorded allowed the suction changes with water evaporation and the behaviour of tracks under the effect of temperature to be analysed. Moreover, the recorded data of acceleration allowed assessing the double-integration method for different kinds of train. It was observed that the site is out of the hazards related to freeze/thaw and the double-integration method can be applied to determine the particle velocity and displacement provided that appropriate filters are used. Note however that further study is needed to confirm this point with comparison between the measured particle displacement and the calculated one. © 2014 Elsevier Ltd.

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